1. Field of the Invention
The present invention relates to a substrate processing apparatus for coating, for example, a semiconductor wafer with a resist solution, followed by developing the resist film after the light exposure, and a substrate transferring method in a substrate processing apparatus.
2. Description of the Related Art
In the manufacture of, for example, a semiconductor device, employed is a photolithography technology in which a semiconductor wafer is coated with a resist solution so as to form a resist film, followed by exposing the resist film to light by using a photo mask and subsequently developing the resist film after the light exposure so as to form a desired resist pattern on the substrate. It was customary in the past to use a resist coating/developing system for carrying out the series of processes described above.
The particular resist coating/developing system is equipped with various process units for individually carrying out a series of processes required for the resist coating and the developing processing. For example, the particular system is equipped with a process station provided with various process units for carrying out a resist coating for coating a wafer with a resist solution, a developing processing for developing the wafer after completion of the light exposure, and a heat treatment for heating the wafer after the resist coating or after the developing processing. Also, since the resist coating/developing system is arranged adjacent to a light exposure device, the resist coating/developing system is equipped with an interface station provided with a wafer transfer device for transferring the wafer into and out of the light exposure device.
In general, the light exposure device includes a transfer-in stage on which a wafer is disposed for transferring the wafer into the light exposure device and a transfer-out stage on which the wafer after completion of the light exposure is disposed for transferring the wafer out of the light exposure device. During the processing of the wafer, the light exposure device and the resist coating/developing system are put in an in-line state, i.e., the state that the bidirectional communication of a control system is established, in order to carry out smoothly the transfer of the wafer between the light exposure device and the resist coating/developing system.
The light exposure device transmits a signal for permitting the transfer of the wafer into the transfer-in stage, hereinafter referred to as a “permitting signal”, or a signal for inhibiting the transfer of the wafer into the transfer-in stage, hereinafter referred to as an “inhibiting signal, to the resist coating/developing system. For example, a wafer transfer device arranged in the interface station transfers the wafer from a prescribed unit arranged in the process station into the transfer-in stage in accordance with the permitting signal. On the other hand, where an inhibiting signal is transmitted from the light exposure device, the wafer transfer device is controlled not to transfer the wafer into the transfer-in stage.
The light exposure device also transmits a signal for designating the transfer of the wafer out of the transfer-out stage, hereinafter referred to as a “transfer-out designating signal”, to the resist coating/developing system. For example, the wafer transfer device arranged in the interface section transfers the wafer out of the transfer-out stage into a prescribed unit arranged in the process station in accordance with the transfer-out designating signal. On the other hand, where a transfer-out signal is not transmitted from the light exposure device, the wafer transfer device is controlled not to be capable of gaining access to the transfer-out stage.
However, there is a case where the wafer transfer device takes out the wafer from a prescribed unit of the process station in accordance with a permitting signal from the light exposure device and, then, an inhibiting signal is transmitted from the light exposure device so as to inhibit the transfer of the wafer onto the transfer-in stage. In this case, the wafer transfer device is held stationary while holding the wafer. Alternatively, the inhibiting signal is neglected so as to cause the wafer transfer device to transfer the wafer onto the transfer-in stage.
It should be noted that, where the operation of the wafer transfer device is stopped while holding the wafer, it is impossible to carry out the other operation, e.g., the operation to bring the wafer after completion of the light exposure treatment back to the process station, because the wafer transfer device keeps the holding state of the wafer until the light exposure device transmits the next permitting signal. As a result, it is possible for the necessity of stopping the processing of the wafer in the process station to be generated. On the other hand, where the inhibiting signal is neglected so as to cause the wafer to be transferred onto the transfer-in stage, it is possible for the delivery of the wafer onto the transfer-in stage to result in failure so as to generate problems. For example, the wafer drops down so as to be broken. Also, damages are done to the wafer transfer device or the transfer-in stage.
Also, there is a case where the wafer transfer device is urged in a manner to gain access to the transfer-out stage upon transmission of a transfer-out designating signal from the light exposure device and, then, the transfer-out designating signal is cut off before completion of the access. In this case, the wafer transfer device is held stationary until the transfer-out designating signal is transmitted again from the light exposure device. Alternatively, the cutting off of the transfer-out designating signal is neglected so as to cause the wafer transfer device to be urged to gain access to the transfer-out stage.
Where the wafer transfer device is held stationary until the transfer-out designating signal is transmitted again, the transfer of the wafer is not carried out between the process station and the light exposure device. On the other hand, where the inhibiting signal is neglected so as to cause the wafer transfer device to be urged to gain access to the transfer-out stage, it is possible for the delivery of the wafer to result in failure so as to give rise to problems. For example, the wafer drops down so as to be broken. Also, damages are done to the wafer transfer device and the transfer-out stage.